Ciudad Juarez, Mexico (CNN) -- At least five men were killed when attackers wielding assault rifles raided a bar in this violence-plagued Mexican border city over the weekend, authorities said.

At least nine others were injured during the attack, which occurred early Sunday morning after people had packed the "Desesperados" bar to watch the Manny Paquiao-Anotonio Margarito boxing match, Chihuahua state prosecutors said.

Witnesses told investigators that several of the alleged assailants guarded the bar's doors while others entered to locate their targets.